Granted Patent
Utility
US 5,135,652 · App. 07/603,065
Method for the solvent extraction of zinc
Inventor:
Daniel A. D. Boateng
Patented Case
View Patent ↗
Granted: Aug 4, 1992
Filed: Oct 25, 1990
Inventor
Daniel A. D. Boateng
Assignee (at issue)
Cominco, Ltd.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.